You really don't think Del Potro can get back to his 2009 form? I think he is very dangerous on fast hard courts. He has excellent movement for someone his size and his serve is downright nasty.
With nasty you mean horrible, right?
His serve is terrible for a guy his size. Even when he won the US Open, he had to basically fight for every point in the final, got pretty much no free points on serve. It's definitely an area where he has to improve tremendously. A guy his size shouldn't be serving like a WTA player, I'm hoping to see improvements on the serve asap. I'm not asking him to serve like Isner or Karlovic, but there's no reason why someone his size can't get one or two free points per service game at least.